1. Field of the Invention
The invention relates generally to seismic energy vibrators and, more particularly, but not by way of limitation, it relates to an improved form of vibration apparatus wherein selected combinations of compressional and shear wave energy are generated simultaneously for input to the earth.
2. Description of the Prior Art
Any such form of purposefully generating simultaneously both compressional and shear wave energy for seismic exploration purposes has not been known heretofore. Successive generations of shear waves and compressional waves from the same source point with reception of received reflection data, correlation and processing comparison for purposes of determining shear/compressional velocity differences was taught in U.S. Pat. No. 3,302,164 in the name of the present inventor as entitled "METHOD AND APPARATUS FOR GEOPHYSICAL PROSPECTING WHICH UTILIZES BOTH REFLECTED SHEAR AND PRESSURE WAVES". Individual teachings of shear wave vibrators and compressional wave vibrators functioning singularly are taught by respective U.S. Pat. Nos. 3,159,233 and 3,306,391, as owned by the present assignee, but none of these prior teachings contemplate or even approach the present method and apparatus which allows simultaneous generation at the same surface source point of both compressional and shear seismic waves.